We will investigate the biological properties of molecules labeled using bifunctional chelates with the aim of developing clinically useful tumor localizing agents. We will study two new derivatives of bleomycin, BLEDTA II and BLEDTA III, as well as the protein chelate conjugates of transferrin and monoclonal antibodies. Radiotracer kinetics and electron microscope autoradiography will be used to study the binding to putative receptors on the tumor cell surface, the mechanisms of transport into the cell cytosol and the metabolism by the cell. We will use chemical, radiochemical, enzymatic and immunologic strategies to maximize tumor concentration while lowering the blood background using a tumor mouse model of BALB/c mice bearing KHJJ tumor. We will test in vitro and in vivo tumoricidal properties of the best "carriers", containing Auger or alpha particle emitters, redox groups, photoreactive groups or covalently bound antitumor drugs. The best tumor imaging agents will be selected for the study of dosimetry, sensitivity and specificity of cancer localization in cancer patients.